Seasonal variation in the song structure of tui (Prosthemadera novaeseelandiae)

Birdsong has evolved to help individual birds attract mates and defend territories. The breeding season is a critical period in the life history of many songbird species and previous studies indicate that bird vocal behaviour changes at the onset of breeding season. In this study, we compared the complex songs of a seasonal-breeding New Zealand honeyeater, the tui (Prosthemadera novaeseelandiae), between breeding and non-breeding seasons. We found that males' songs in the breeding season contained significantly greater proportions of trill components compared with songs in the non-breeding season. Trill rate and consistency may be related to individual quality and therefore might signal to rivals and potential mates the quality of the singer. This is the first study to show the differences in singing behaviour of tui between seasons and provides a basis for future studies to explore the drivers of this seasonal variation in song behaviour.